It is known to monitor battery state of charge during periods of shut-down and to use the monitored state of charge to prevent battery depletion before the next start-up event. Although this start-up function may be the primary function of a battery, batteries are also used to power auxiliary systems during periods of shut-down or park cycles. These auxiliary power drains are parasitic loads upon the battery. A monitoring system may be utilized during park cycles to sample the state of charge available from the battery at periodic intervals. This state of charge may then be compared to some threshold state of charge value to determine whether the battery has lost enough charge to pose a risk to the next start-up event. However, known sampling and comparison methods may be inaccurate or slow to indicate abnormal conditions. One factor in slow indications is the long periods that tend to exist between actual state of charge sampling events. Measuring actual state of charge is an operation that in itself depletes some battery charge. It is undesirable that the very system meant to warn of low battery charge be a primary contributor to the battery drain.
It is desirable to generate from available sensor readings a predicted start-up state of charge that can be utilized to forecast anomalous situations in which the next start-up cycle is at risk due to excessive battery parasitic load.